Water diffusion in many biological tissues, including brain, is non-Gaussian. This non-Gaussianity is conveniently quantified with diffusional kurtosis, which can be estimated with a diffusion magnetic resonance imaging (MRI) technique known as diffusional kurtosis imaging (DKI). The diffusional kurtosis can be used for characterizing tissue microstructure, providing information related to microscopic (e.g., intra-voxel) diffusional heterogeneity. Accordingly, DKI has been applied to the study of a variety of neurological diseases.
Standard DKI utilizes conventional single pulsed field gradient (s-PFG) diffusion sequences, which have a single diffusion wave vector, q, for each signal acquisition. Recently, there has been a growing interest in double pulsed field gradient (d-PFG) diffusion sequences, which have a pair of diffusion wave vectors, (q, q′), for each signal acquisition. Such d-PFG diffusion sequences (also referred to as double-wave-vector sequences) yield information beyond that available with s-PFG diffusion sequences. For example, d-PFG diffusion sequences can detect microscopic diffusional anisotropy even when the data from the s-PFG diffusion sequences is isotropic. However, despite the advantages of d-PFG diffusion sequences, these d-PFG diffusion sequences have not been applied to DKI.